1. Field of the Invention
The present invention relates to coaxial jack constructions, and particularly to a coaxial jack having an internal switch mechanism.
2. Discussion of the Known Art
Type 440 coaxial jacks, which are compatible with type 440 plugs, are known generally for use in telephone cross-connect systems. One such system, known as System III DSX-3/4, has been used in telecommunication networks in the United States for the past seven years. The system is used to cross-connect DS3, STS1, STS3 or DS4 level signals manually at a central office.
A building block of the System III DSX-3/4 is called a DSX-3/4 module. This module has a 3-inch by 3-inch by 0.5 inch die cast metal case. The case houses a jack set comprised of five conventional type 440 jacks, and three mechanical switches interposed externally between four of the jacks. The switches have activators and contacts that enter side openings in the jack barrels to sense an inserted plug. See, e.g., U.S. Pat. No. 4,815,104 (March 1989). The five type 440 jacks open on a front panel of the case, and two bulk head type BNC jacks are mounted on a rear panel of the case. Other components inside the case include two hand-soldered coaxial cables, a metal housing for the five type 440 jacks, three resisters, and one inductor. The module is also known as a 1201A jack set.
The internal component layout in the 1201A jack set is very difficult to modify. This makes additional features very difficult to provide, since only a limited number of coaxial cables can fit inside the jack set, and routing the cables requires extreme care to maintain consistent transmission performance. It would therefore be desirable to incorporate a printed wiring board in a 1201A jack set for mounting of all components and routing all signal lines. See U.S. Pat. No. 5,233,501 (August 1993)
Another cross-connect system, the DIXI-3, has been used in telecommunication networks in the United States for the past three years. The DIXI-3 system is used to interconnect and cross-connect DS3, STS1 and STS3 signals manually in a central office.
A building block of the DIXI-3 system is the DIXI-3module. This module has a 0.75-inch by 5.5-inch by 6.0-inch plastics case which houses a printed wiring board with eight right-angle BNC connectors. Because the DIXI-3 system is a rear-cabled rear cross-connected system, four BNC connectors are located at a rear end of each module and four BNC connectors are located at a front end of the module. The BNC connectors at the rear are for cabling and cross-connecting operations, and the BNC connectors at the front are for patching and monitoring. Migration from the earlier mentioned DSX-3 system with 440 jacks to a DIXI-3 system, would be simplified if the BNC jacks for patching and monitoring on the DIXI-3 modules are replaced by type 440 jacks. Thus, there is also a need for a type 440 coaxial jack that is right-angled with an internal switch, and which is easily mountable on printed wiring boards of the kind used in existing systems.